The AR-15 was first built as a small arms rifle for the United States armed forces. Later on, the AR-15 was made available for civilian sales in 1963. As in most rifles, the AR-15 uses an operation mechanism called direct gas impingement, in which gas from a fired cartridge is directly guided to the bolt carrier or slide assembly to cycle the action. The AR-15 is designed such that one upper receiver can quickly and easily be substituted for another. Therefore, the upper receiver can incorporate barrels of different weights, lengths, and calibers.
The barrel of the AR-15 is attached to the front end of the upper receiver. The attachment point on the standard upper receiver is considerably thin and is prone to cracking. As a result of the lack of strength, parts need to be replaced on a regular basis. Once the barrel is placed within the upper receiver, the position of the barrel is secured by the barrel nut. The gas system is attached afterwards. In doing so, the gas tube of the gas system is inserted through a slot in the barrel nut. Therefore, when the barrel needs to be changed, the entire gas system and the barrel nut needs to be removed. The process of removing the gas system and the barrel nut can be time consuming and stressful. The time consuming nature of the process can be disadvantageous to an individual who disassembles AR-15s on a regular basis. Furthermore, due to the thin attachment point provided on a standard AR-15, repeated changing of barrels can affect life span of the weapon due to cracking. The tedious process of aligning and tightening of components needs to be repeated since the entire gas system is removed along with the barrel. As a result of the repeated use, even the components that were not replaced wear off to some extent.
The objective of the present invention is to address the aforementioned issues. The effective design of the present invention allows a user to conveniently interchange the barrel. As mentioned earlier, the barrel of a standard AR-15 is secured using a barrel nut. Instead of securing the barrel with the use of a barrel nut, the present invention allows the barrel to be securely positioned within the body of the upper receiver. More specifically, the present invention uses an internal barrel nut. Instead of being connected to the barrel nut, the gas tube is separately connected to the upper receiver which allows the barrel to be removed and changed without interrupting the gas system. Additionally, it has been experimentally proven that the present invention is flexible, durable, and reliable under the harshest conditions.